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| Title | Display a directory structure in a TreeView controls, and save and restore the hierarchy in a file |
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| Description | This example shows how to display a directory structure in a ListView control in Visual Basic 6. It also saves the structure in a text file using indentation to show the hierarchy's structure and shows how to load the structure back into a TreeView control. |
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| Keywords | TreeView, directory, directory hierarchy |
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| Categories | Controls, Files and Directories |
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Thanks to Sergio Perciballi.
When you click the Go button, the program gets ready, opens a text file, and calls subroutine Get_Files.
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Private Sub cmdGo_Click()
Dim x As Integer, S$
Dim file_name As String
file_name = App.Path
If Right$(file_name, 1) <> "\" Then file_name = _
file_name & "\"
Open file_name & "Mytest.txt" For Output As #1
Text1.Text = ""
TreeView1.Nodes.Clear
file_name = txtPath.Text
If Right$(file_name, 1) <> "\" Then file_name = _
file_name & "\"
Text1.Text = Text1.Text & file_name & vbCrLf
' need \ on end of key here------------|
Set fnode = TreeView1.Nodes.Add(, , file_name, _
file_name)
'initial data to file; topmost root of tree
Print #1, file_name
'initialise variables
FIndent = 1
FIndex = 0
Text1.Visible = False
TreeView1.Visible = False
LblPrompt.Caption = "Processing drive..."
LblPrompt.Refresh
'note does not end with '\'
StrtPath = Left$(file_name, Len(file_name) - 1)
'start the directory reading
Get_Files StrtPath
Text1.Visible = True
TreeView1.Visible = True
LblPrompt.Caption = "Finished"
Close 1
End Sub
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Subroutine Get_Files uses the Dir$ command to get the subdirectories inside a directory. It prints the subdirectory names into the text file and adds nodes for them in the TreeView control. It recursively calls itself to get the files contained in the subdirectory.
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Private Sub Get_Files(FPath As String)
Dim file_name As String
Dim File_Path As String
Dim File_Read As Integer
Dim x As Boolean, xTemp As Integer, S$
Dim I As Integer
On Error Resume Next
FIndent = FIndent + 1
File_Path = FPath & "\"
file_name = Dir$(File_Path, vbDirectory)
File_Read = 1
x = False
Do While file_name <> ""
If file_name <> "." And file_name <> ".." Then
If GetAttr(File_Path & file_name) <> _
vbDirectory Then
FIndex = FIndex + 1
Else
StrtPath = File_Path & file_name
Set fnode = TreeView1.Nodes.Add(File_Path, _
tvwChild, FPath & "\", file_name)
'changed to dash/hyphen for readability
Text1.Text = Text1.Text & "->" & _
String(FIndent * FIndent, "_") & _
file_name & vbCrLf
S$ = ""
''possible hack ; if FIndent=1 this doesn't
' execute
For xTemp = 2 To FIndent
S$ = S$ & vbTab
Next
'write to a file; number of levels= number
' of tabs
Print #1, S$ & file_name
FIndex = FIndex + 1
x = True
'recursive call
Get_Files StrtPath
End If
End If
If x = True Then
file_name = Dir$(File_Path, vbDirectory)
For I = 2 To File_Read
file_name = Dir$
Next
x = False
End If
file_name = Dir$
File_Read = File_Read + 1
Loop
FIndent = FIndent - 1
End Sub
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Subroutine LoadTreeViewFromFile loads the text file into a TreeView control. It uses "Line Input" to read the files' lines. For each line, it counts the number of Tab characters at the beginning of the line and adds the new directory name to the appropriate level in the TreeView control.
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Private Sub LoadTreeViewFromFile(ByVal file_name As String, _
ByVal trv As TreeView)
Dim fnum As Integer
Dim text_line As String
Dim level As Integer
Dim tree_nodes() As node
Dim num_nodes As Integer
fnum = FreeFile
Open file_name For Input As fnum
trv.Nodes.Clear
Do While Not EOF(fnum)
' Get a line.
Line Input #fnum, text_line
' Find the level of indentation.
level = 1
Do While Left$(text_line, 1) = vbTab
level = level + 1
text_line = Mid$(text_line, 2)
Loop
' Make room for the new node.
If level > num_nodes Then
num_nodes = level
ReDim Preserve tree_nodes(1 To num_nodes)
End If
' Add the new node.
If level = 1 Then
Set tree_nodes(level) = trv.Nodes.Add(, , , _
text_line)
Else
Set tree_nodes(level) = _
trv.Nodes.Add(tree_nodes(level - 1), _
tvwChild, , text_line)
'tons faster without this
''tree_nodes(level).EnsureVisible
End If
Loop
Close fnum
End Sub
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